1. Field of the Invention
The present invention relates to a chord detecting/storing apparatus and an accompaniment information processing apparatus to be used in, for example, an electronic musical instrument. More particularly, the present invention pertains to a chord detecting/storing apparatus which has a smaller chord table for chord detection and can quickly detect a chord, and an accompaniment information processing apparatus to detect a tone selected on a keyboard, etc, and to store that tone as accompaniment information after it has received predetermined processing.
2. Description of the Related Art
A chord detecting/storing apparatus to be used in an electronic musical instrument or the like is disclosed in, for example, Japanese Patent Examined Publication No. 56-51630 as prior art. To acquire (detect) chord information, this prior art apparatus has a chord table where only a chord type with "C" as a chord root is stored, sequentially compares note bit information produced by depressing a key with the chord table, and repeats a rotational shift until the bit information matches that in the chord table.
This chord detecting/storing apparatus does not need a large chord table; however, it has many processes difficult for a current central processing unit (CPU), such as sequential comparison and rotational shift, and requires much time for chord detection.
Another chord detecting/storing apparatus is disclosed in Japanese Patent Examined Publication No. 62-27717. This apparatus has a chord table which stores all chord patterns, with note "C" being ON. The apparatus detects a chord by rotationally shifting note bit information produced by depressing a key until an ON bit appears at the note "C," and sequentially compares the information with the chord pattern.
According to this invention, processing time is reduced since only one rotational shift is required. The apparatus in this invention, however, though performing a rotational shift, uses a chord table having all note bits as addresses, so that a chord table stored in a memory, such as in a ROM, cannot effectively be utilized.
Further, another chord detecting/storing apparatus is disclosed in Japanese Patent Examined Publication No. 62-27717. This apparatus includes a chord table showing all note bit information. The apparatus uses note bit information produced when a key is depressed as an address pointer into the chord table, thus detecting a chord directly.
In this invention, however, an enormous chord table of "2.sup.12 " is necessary.
As an example of an accompaniment information processing apparatus to be used in an electronic musical instrument or the like, an electronic musical instrument with an automatically playing apparatus is disclosed in Japanese Patent Unexamined Publication No. 62-187388. The apparatus in this invention is designed to store the chord type and chord root of a chord only when that chord is established by key depression on a keyboard.
Another example of an automatically playing apparatus as an accompaniment information processing apparatus is disclosed in Japanese Patent Unexamined Publication No. 1-179087. This apparatus is designed to store the chord type and chord root of a chord when it is established, and to store an unspecified number of chord component tones when the chord is not established.
The inventions disclosed in both publications provide a predetermined effect with respect to efficient storage of chord information; however, they have the following shortcomings.
(1) Since only the chord type and chord root of a chord are stored when that chord is established, the lowest note on a keyboard cannot be determined. Nor can it be determined in which octave the chord is produced. In reproducing a chord, therefore, the only possible process is a fixed one of setting a chord root at the lowest note and reproducing that in a specific octave. Thus an accompaniment cannot be accurately reproduced.
(2) Since chord component tones are stored by the note when the chord is unestablished, the amount of information to be stored increases accordingly.
(3) When a chord is unestablished, Major or special information for no chord establishment is stored and reproduced as an accompaniment pattern, providing an accompaniment which is far from real and natural.
(4) Whether a chord is established and the chord, if established, is stored is carefully checked, but a key-ON condition cannot be detected in an accompaniment area to be stored.